Ben Stiller’s life was saved because he had a screening test for prostate cancer. Now he’s urging others to follow his lead. Stiller’s logic sounds irrefutable. But he’s dead wrong.
The US actor is a test that detects blood levels of prostate-specific-antigen, or PSA, a substance produced by the prostate gland; higher levels may suggest a tumour. After a worrying result, Stiller was diagnosed with prostate cancer two years ago, at just 48. After a biopsy and surgery, he is now cancer free.
So should other men rush out to get tested? Absolutely not, because the PSA test is a bad one. Levels can be high for reasons other than cancer, like an infection – and even after further tests, the screening process may only find slow-growing cancers that would never have been fatal.
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But surely there is no harm in getting tested anyway, just in case? The trouble is that treatments for prostate cancer are awful. Surgery or radiotherapy, and even the initial biopsy, can cause impotence and incontinence that could otherwise have been avoided.
We all instinctively dread cancer, but tumours of the prostate are usually a different breed to cancer in other organs. Most prostate cancers grow slowly, which is why post-mortems find such tumours, apparently not causing any problems, in up to two-thirds of elderly men who die from other causes.
Treatment toll
Some prostate cancers break this rule and are fast growing, but we have no way of identifying this small fraction of dangerous ones. Actors’ personal stories, no matter how compelling, cannot tell us how any gains from PSA screening compare with the toll treatment takes on men’s bodies – only large randomised trials can do that.
And such trials show that screening doesn’t reduce the death rate one little bit, suggesting it mainly finds those slow-growing cancers that, left alone, would have caused no harm.
They also show that for every 1000 men who have the PSA test, two will have their life saved, but seven to ten will end up with .
For these reasons, the UK National Screening Committee recommends we – not to save money, but to save men’s health. Even many US doctors, who are typically more gung-ho about medical interventions than their European colleagues, .
That doesn’t mean that men shouldn’t bother going to their doctor if they have possible symptoms of prostate cancer, like frequent peeing, or difficulty in peeing. Those risk-benefit numbers only apply to men who had no symptoms to start with.
To be fair to Stiller, his acknowledged some of the problems with the PSA test, but these nuances were lost in much of the news coverage. And he still concluded with the misleading aphorism that the best option for this deadly cancer is to detect it early.
It’s a simple and appealing message, but as is often the case with stories from Hollywood, the truth is a lot more complicated.
